NASA Technical Reports Server (NTRS) 20150019641: Huygens Crater: Insights into Noachian Volcanism, Stratigraphy, and Aqueous Processes

First Landing Site/Exploration Zone Workshop for Human Missions to the Surface of Mars (2015)

1032.pdf

HUYGENS CRATER: INSIGHTS INTO NOACHIAN VOLCANISM, STRATIGRAPHY, AND AQUEOUS
PROCESSES. S. E. Ackiss 1 , J. J. Wray 2 , K. D. Seelos 3 , and P. B. Niles 4 , ! Dept. of Earth, Atmospheric, and Plane-
tary Sciences, Purdue University, West Lafayette, IN (sackiss@purdue.edu), 2 School of Earth & Atmospheric Sci-
ences, Georgia Institute of Technology, Atlanta, GA, 3 Johns Hopkins University Applied Physics Laboratory, Laurel,
MD, 4 NASA Johnson Space Center, Houston, TX.

Rationale: Huygens crater (Figure 1) is a well pre-
served peak ring structure on Mars centered at 13.5°S,
55.5°E in the Noachian highlands between Terras Tyr-
rhena and Sabaea near the NW rim of Hellas basin.
With a diameter of -470 km, it uplifted and exhumed
pre-Noachian crustal materials from depths greater
than 25 km, penetrating below the thick, ubiquitous
layer of Hellas ejecta. In addition, Huygens served as a
basin for subsequent aqueous activity, including ero-
sion/deposition by fluvial valley networks and subsur-
face alteration that is now exposed by smaller impacts.
Younger mafic-bearing plains that partially cover the
basin floor and surrounding intercrater areas were like-
ly emplaced by later volcanism.

Regional Geology: Noachian Crustal Units: Huy-
gens and the surrounding region has been mapped as
early to late Noachian in age with one outcrop of mid-
dle Noachian aged material partially covering the
crater floor from the western wall eastward to the peak
ring [1]. Mineralogy of Huygens has been examined in
detail as well [2]. Two types of plains delineated with-
in Huygens consist of olivine-rich and high-calcium
pyroxene (HCP)-rich units, both of which exhibit rela-
tively high thermal inertia and lack large amounts of
eolian materials (e.g. dunes). As described in [3], the
most probable origin of the mafic plains is effusive
volcanism, where magma rose to the surface via a
dense network of fractures created by the Hellas im-
pact. Subsequent impacts also could have initiated
magma formation and assent through decompression
melting [4], as craters in the region are also commonly
filled with mafic-rich, high thermal inertia material.
Exposures of low calcium pyroxene (LCP) occur as
well, usually in distinct massif-forming terrain that may
be remnants of deep crustal material exhumed by the
Hellas impact. LCP-bearing outrcrops are predomi-
nantly located outside Huygens but a few occurrances
have been identified on the floor.

Aqueous Alteration: Aqueously altered materials
are identified both inside (on the floor of) and outside
Huygens and include Fe/Mg smectites, Al-bearing
phyllosilicates, and Fe/Ca carbonates (see also [5]).
These minerals are observed in crater rims/walls, cen-
tral peaks, and ejecta of smaller subsequent impacts,
and therefore inferred to have formed in the subsurface
prior to the impacts, not via impact-driven, hydrother-
mal alteration [6, 7]. Aqueous alteration could have
coincided with formation of fluvial valley networks

post-Huygens or may have been pre-exisiting (or both);
no spatial relationship between alteration mineral out-
crops and Huygens-related structures is evident.

Biosignature and Habitability Preservation Poten-
tial: The carbonates within the Huygens basin (exposed
by the cratering process) are associated with phyllosili-
cates and occupy layered rocks [5]. These materials
record ancient neutral-to-alkaline fluid chemistry of at
least regional extent, and may be an important reservoir
for paleo-atmospheric CO 2 . If formed via subaqueous
sedimentation, their preservation potential is high, and
in any case their isotope systematics will be valuable
tracers of magmatic, atmospheric, and biochemical
processes.

Stratigraphic Context and Cross Cutting Relation-
ships: While the Huygens impact itself and all mapped
surface units date from early to late Naochian, a finer
relative stratigraphy may be discerned using mineralog-
ic information. If the LCP-bearing massifs do indeed
represent excavated deep crust from the Hellas impact,
this is the oldest exposed material in the region. The
Huygens impact panetrated through the Hellas ejecta
blanket, potentially sampling pre-Hellas crust and up-
lifting/redistributing any pre-exisiting alteration miner-
als. Post-Huygens the surface was modified by fluvial
activity, with associated ground water potentially lead-
ing to the formation of subsurface alteration minerals.
The mafic plains units are the youngest materials, and
embay the fluvially dissected terrain. By sampling
these types of materials and depositional environments,
a mission to Huygens would arguably be exploring the
most geologically active time period in martian history.

Acknowledgements: K. S. thanks NASA Mars Da-
ta Analysis Program (grant number NNX10AO25G).
S. A. thanks an appointment at the JHU Applied Phys-
ics Lab (APL) administered by the Oak Ridge Institute
for Science and Education through an agreement be-
tween the U.S. DOE and APL; J. W. thanks the
MRO/CRISM and MRO/HiRISE teams for support.

References: [1] Tanaka et al. (2014), Geologic
map of Mars: U.S. Geological Survey Scientific Inves-
tigations Map 3292, [2] Ackiss et al. (2014), Eighth
Mars Conference, Abstract #: 1038, [3] Rogers and
Nazarian (2013), JGR: Planets, 118(5), 1094-1113 [4]
Edwards et al. (2014), Icarus , 228, 149-166, [5] Wray
et al. (201 1), LPSC 42, Abstract #: 2635. [6] Ehlmann
et al. (201 1), Nature , 479(7371), 53-60, [7] Loizeau et
al. (2012), Icarus , 219, 476-497 .

First Landing Site/Exploration Zone Workshop for Human Missions to the Surface of Mars (2015)

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Figure 1 . Huygens crater exploration zone over MOL A topography with 2km elevation denoted. Inset shows loca-

tion on the globe. Black circles indicate resource regions of interest and white cirlces indicate regions covered with

expanisve mafic material. Landing site 1 has a larger phyllosilicate/carbonate deposit and mafic plains that can be

age dated while Landing site 2 gives access to the crater wall and valley networks that flow into the crater.